With an initial emphasis on the hippocampus, the research is designed to identify the behavioral correlates of enhanced multiple unit activity in rabbits and cats during aversive Pavlovian conditioning. Since this activity is identifiable on a trial-by-trial basis in individual organisms it is possible to (1) link the emergence and any subsequent changes in multiple unit activity to individual-subject parameters of a mathematical model of aversive conditioning, (2) determine the extent to which this activity is correlated with contingency detection and memory storage as opposed to response genration, and (3) increase our understanding of the conditioning processes associated with the parameters of a mathematical model.